Primary Aortic Malignant Peripheral Nerve Sheath Tumor

A 74 year-old woman suffering 1 month persisting lumbago was referred with diagnosis of thoracic aortic aneurysm. Blood examinations indicated slightly or moderately elevated noradrenaline, dopamine, and homovanillic acid with normal-range vanillylmandelic acid. Contrast-enhanced CT scans revealed a tumor, protruding both intra- and extra-luminally, in the wall of the distal descending thoracic aorta without any primary focuses in the whole body. Primary aortic sarcoma or periaortic catecholamine-producing paraganglioma infiltrating the aorta was suspected. The tumor with the normal proximal and distal aorta 2-3 cm apart from it was completely resected under femoro-femoral partial cardiopulmonary bypass. Macroscopically, the tumor was originated from the aortic wall and protruded both intra- and extra-luminally. Immunohistochemically, positive S-100 and vimentin; Ki67 levels of 40%; and negative CD34, CK AE1/AE3, and SMA were identified. The aforementioned findings definitively diagnosed primary aortic malignant peripheral nerve sheath tumor, which has been never reported in the literature.